Log structures have been built for centuries. Historically, log structures were handcrafted using logs in their natural shape. That is, using logs that retain the unique, natural shapes of the trees from which they came. More recently, log buildings have been constructed using prefabricated logs. For example, such logs are commonly manufactured to have a common shape, whereby they can be used interchangeably. While prefabricated log structures can be built more quickly and affordably than those built by hand, many people prefer the aesthetics of a handcrafted log home. Accordingly, handcrafted homes remain popular even though their construction commonly involves significant time and expense.
The general procedure used in log construction developed long before the advent of cranes and other mechanized lifting equipment. Because logs are heavy, awkward, and dangerous to lift, early log builders did not want to lift logs onto a wall more than once. Thus, once each log was positioned upon a wall, it was processed completely until it fit in its permanent position on the wall. Only then would the next log be processed. Thus, at any given time, only the logs that were on the exposed top layer would be processed. Even though this general procedure was invented for log construction without modern lifting equipment, this procedure is used even today by those who build handcrafted log homes. This traditional procedure will now be described as it would typically be applied in building a simple four-walled structure.
Each log is processed one-at-a-time through a series of steps to produce a handcrafted log structure. First, a set of logs are selected and the bark is removed from each log. The first-layer logs are then selected and positioned. Traditionally, each of the first-layer and second-layer logs (or “sill logs”) is cut to have a planar bottom surface that will rest on the floor deck to provide the structure with a solid foundation. Two first-layer logs are positioned in a parallel, spaced-apart configuration.
(In the present background section, terms like “first-layer” and “second-layer” logs are used to refer to the two layers of logs that are closest to the ground. Throughout the rest of this disclosure. for example, and unless otherwise specified, in the assemblies and methods described in the detailed description section, terms like “first-layer logs” and “second-layer logs” are used simply to refer to logs of any two adjacent layers, even though those logs need not ultimately be the two layers that are closest to the ground in the resulting shell.)
Each additional layer comprises two logs that are stacked crosswise over the logs of the layer below. For example, the second-layer in such a structure comprises two logs positioned in a crosswise stack on top of the first-layer logs. A notch is marked near both ends of each second-layer log, then the notches are cut, whereafter the second-layer logs are re-stacked over the first-layer logs with each notch fitted over the end of a first-layer log. The notches in the second-layer logs are commonly dimensioned such that the planar bottom surfaces of the second-layer logs will be flush with the planar bottom surfaces of the first-layer logs when these notches are fitted over the first-layer logs.
Once the first-layer and second-layer logs are in place and fitted, the third-layer logs are selected and lifted into place. Each third-layer log is positioned in a crosswise stack atop the second-layer of logs such that each third-layer log lies directly above a first-layer log. At this stage, there is a gap between each pair of adjacent first-layer and third-layer logs. This gap will often be wider at one end than at the other. Both ends of this gap are measured to determine how the adjacent third-layer log can be lowered to make the gaps more uniform from end to end. A rough notch is then cut into the end of the third-layer log that is adjacent the wide end of the gap. The depth of this rough notch is such that when it is fitted over the second-layer log below, the third-layer log is lowered to a position where the vertical height of the gap is about the same at both ends. Commonly, a rough notch is cut into both ends of each third-layer log so each gap is made to be both less tall and more uniform. But it is not uncommon for no rough notches to be cut at all, or for rough notches to be cut in only one end of a log, instead of both ends, of a given log.
Even after rough notching, there will commonly be one area where the gap between each pair of adjacent first-layer and third-layer logs is greatest. This is because each log has a unique and irregular shape that corresponds to the natural shape of the tree from which it came. The maximum height of this gap is measured for each pair of adjacent first-layer and third-layer logs.
A marking instrument similar to an inside caliper is then used to mark (or “scribe”) a long groove that will be cut in the bottom surface of each third-layer log. The marking points of the caliper (or “scriber”) are set to a distance (the “scribe setting”) that is slightly greater than the maximum gap height that was found for that particular pair of adjacent first-layer and third-layer logs. Because the maximum gap between each pair of adjacent first-layer and third-layer logs will commonly be different, the scribe setting for each such pair of logs will likewise be different.
The scriber is used to mark a final notch cut on both ends of each third-layer log. The scriber is used to mark a final notch cut that will lower each end of each third-layer log by the same distance that was used to mark the long groove cut for that pair of logs.
The long groove and the final notches are then cut for each third-layer log. This is commonly done by rolling each third-layer log upside down and cutting the long groove and the final notches that have been scribed. Alternatively, each third-layer log may be removed from the wall and placed near the ground for cutting. Each third-layer log is then put in its finally fitted position. Only after the third-layer logs have been completely processed and fitted into their final position, does the builder begin working on the fourth-layer logs. The same steps are performed for each fourth-layer log until each log in the fourth-layer is fitted into its final position. This process is repeated for each of the remaining logs in the walls of the structure. Thus, each log on the exposed upper layer is fully processed and placed into its final, permanent position before any work is done on logs of higher layers.
As can be seen, the traditional method of fully processing each log one log at a time is inefficient and slow. For example, a four-walled building with nine logs in each wall will comprise 36 logs. However, using the traditional method, only two out of 36 logs are processed at one time. Thus, even a small, simple log structure takes a long time to build with the traditional method. Clients can be frustrated by the slow pace at which handcrafted structures are built. Accordingly, the development of the log building industry has been affected by the high costs and lengthy wait-times that are characteristic of the traditional log-by-log building method.
In short, traditional methods are adequately suited to building on the final foundation and without a crane. However, they are poorly suited to building off-site and with a crane. Traditional methods were adequate in the year 1620, but they are now poor business choices.
Modern mass-production methods typically benefit from using work forces comprised of specialized laborers rather than small work crews of highly-skilled craftsmen. It is difficult to use a large number of workers in traditional log building methodology. Since only a few logs are processed at one time, there is only enough work for a few workers to do. Thus, log building companies typically keep each work crew small. Furthermore, when crews are small, it is useful if each worker is skilled at performing many log construction tasks. This makes specialization of labor difficult. It is also time-consuming and costly to hire and keep workers who are proficient at the full spectrum of tasks. Likewise, it is expensive to adequately train workers in all of the numerous skills required in log building. Furthermore, those workers who become skilled at all aspects of log construction are sometimes tempted to leave employment to start their own log construction business. In summary, log building companies can find employment, training, and maintenance of skilled workers and crews to be a continuing expense.
The traditional method of log building can also be unsafe. It can be difficult and expensive to erect scaffolding around a log structure during construction. Thus, where long grooves are cut into logs that are resting atop walls, workers may be required to walk backwards on top of the log walls while operating a chainsaw. For example, this may be the case where double-cut long grooves are used. This type of groove is disclosed in U.S. Pat. No. 4,951,435, which is issued to Beckedorf (the entire teachings of which are incorporated herein by reference).
It is common to assemble each log shell twice using traditional log building methods. Commonly, the shell is built once at the construction yard and again at its final location. Since each log is fully processed one at a time with the traditional method, this adds significantly to the construction time. This also means that each log is handled many times. Inevitably, there are costs and risks each time that heavy, awkward logs are handled at a construction site. There is a risk of accident each time a log is moved or lifted. Furthermore, the peeled, natural surface of each log can be scratched and dented by lifting tongs. Such damage is undesirable since the peeled surface of the log commonly serves as the finished surface of the walls.
Surprisingly, log home builders today use the same basic procedures that builders were using hundreds of years ago. It would be desirable to provide more efficient methods for building handcrafted structures with naturally-shaped logs. It would also be desirable to provide log-positioning apparatuses that can be used to facilitate efficient log building methods.